libostree/deploy: enable composefs by default

The composefs libostree integration has been supported for a while now
and is actively in use in various ostree/bootc-based systems. Let's
turn it on by default.

This has no effect if composefs support is not compiled in. Note also
that this does not change the default value of the `composefs.enabled`
tristate to `true`. The default is still `maybe`, but the deploy API
will now also create composefs images for `maybe`.

The reason for doing it this way is so that systems upgrading from
old libostree versions (which may either not have composefs support or
may have composefs-related bugs) will still be able to upgrade and not
trip `ostree-prepare-root` in the new deployment (which allows missing
composefs images for `maybe`).

We may in the future change the default value to `true`.

See also: ostreedev#2867

src/libostree/ostree-sysroot-deploy.c

@@ -667,7 +667,7 @@ checkout_deployment_tree (OstreeSysroot *sysroot, OstreeRepo *repo, OstreeDeploy
   g_debug ("composefs enabled by config: %d repo: %d", composefs_enabled, repo->composefs_wanted);
   if (repo->composefs_wanted == OT_TRISTATE_YES)
     composefs_enabled = repo->composefs_wanted;
-  if (composefs_enabled == OT_TRISTATE_YES)
+  if (composefs_enabled != OT_TRISTATE_NO)
     {
       composefs_start_time = g_get_monotonic_time ();
       // TODO: Clean up our mess around composefs/fsverity...we have duplication

tests/admin-test.sh

@@ -71,9 +71,10 @@ assert_not_file_has_content status.txt "pending"
 assert_not_file_has_content status.txt "rollback"
 validate_bootloader
 
-# Someday probably soon we'll turn this on by default, but for now
-if test -f sysroot/ostree/deploy/testos/deploy/*.0/.ostree.cfs; then
-    fatal "found composefs unexpectedly"
+if has_ostree_feature composefs; then
+    if ! test -f sysroot/ostree/deploy/testos/deploy/*.0/.ostree.cfs; then
+        fatal "missing composefs"
+    fi
 fi
 
 # Test the bootable and linux keys

tests/test-admin-deploy-composefs.sh

@@ -26,14 +26,32 @@ skip_without_ostree_feature composefs
 # Exports OSTREE_SYSROOT so --sysroot not needed.
 setup_os_repository "archive" "syslinux"
 
+# check disablement
 cd osdata
 mkdir -p usr/lib/ostree
 cat > usr/lib/ostree/prepare-root.conf << 'EOF'
 [composefs]
+enabled=false
+EOF
+cd -
+
+${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo commit --add-metadata-string version=1.composefs -b testos/buildmain/x86_64-runtime osdata
+${CMD_PREFIX} ostree --repo=sysroot/ostree/repo pull-local --remote=testos testos-repo testos/buildmain/x86_64-runtime
+
+${CMD_PREFIX} ostree admin deploy --os=testos --karg=root=LABEL=foo --karg=testkarg=1 testos:testos/buildmain/x86_64-runtime
+if test -f sysroot/ostree/deploy/testos/deploy/*.0/.ostree.cfs; then
+    fatal "found composefs unexpectedly"
+fi
+
+# check explicit enablement
+cd osdata
+cat > usr/lib/ostree/prepare-root.conf << 'EOF'
+[composefs]
 enabled=true
 EOF
-${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo commit --add-metadata-string version=1.composefs -b testos/buildmain/x86_64-runtime
 cd -
+
+${CMD_PREFIX} ostree --repo=${test_tmpdir}/testos-repo commit --add-metadata-string version=1.composefs -b testos/buildmain/x86_64-runtime osdata
 ${CMD_PREFIX} ostree --repo=sysroot/ostree/repo pull-local --remote=testos testos-repo testos/buildmain/x86_64-runtime
 
 ${CMD_PREFIX} ostree admin deploy --os=testos --karg=root=LABEL=foo --karg=testkarg=1 testos:testos/buildmain/x86_64-runtime